1028 
DE, W. H. GASKELL ON THE EHYTHM OF THE HEART OF 
that the protoplasm does not form the explosive substance directly, but that there are 
intermediate stages corresponding to the zymogenic stage in the gland. According to 
this view there would be in the cardiac muscle during its normal activity three pro¬ 
cesses going on : the growth of the protoplasm with the aid of the raw material from 
the nutritive fluid surrounding the muscle fibres; the transformation of the protoplasm 
into intermediate products, which are non-explosible, or at least explosible with diffi- 
culty ; and the formation from these of easily explosible material; in fact, a gradual 
succession from stable to more and more unstable combinations. If, then, the formative 
activity of the muscle be distributed over these three stages in the right proportion, it 
follows that impulses passing to the muscle at equal times must all cause contractions 
of equal force. If, however, that activity be exclusively directed towards the forma¬ 
tion of the muscle protoplasm or the intermediate non-explosible substances it is con¬ 
ceivable that no contractions should be able to take place, because no suitable material 
was ready for the impulses to act upon, though as a natural consequence of this greater 
activity in the formation of the intermediate substances the ultimate effect would be 
that the subsequent contractions would be very much greater than before. On this 
view, then, the force of the contraction at any time depends upon the relative rates 
at which these three processes proceed. 
In this way I can imagine standstill to take place, and it is also quite conceivable 
that in certain conditions of nutrition of the heart it may occur more easily than in 
others ; thus, as we have seen in the heart cut out and suspended, complete quiescence 
may in some cases be easily obtained, in others not at all; so, also, in the heart through 
which salt solution is flowing I have often obtained standstill upon stimulation of the 
vagus, thus confirming Ludwig and Luciislnger,* while in other cases I have only 
obtained acceleration, thus confirming Schiff.1* 
Again, if the whole heart or the ventricle alone be beating in the apparatus described 
on page 1019, while salt solution is flowing through it, it will beat regularly and well 
for a long time with the salt solution, and if while it is still beating, whether strongly 
or weakly, blood solution be sent into it under the same conditions of pressure, &c., as 
the salt solution, then it often happens that as soon as the blood is seen to reach the 
heart or the ventricle the heart stops still in the relaxed condition, sometimes for a 
considerable length of time, and subsequently begins again to beat with the improved 
beats due to the blood solution. In the same heart this experiment may be repeated 
again and again; in other hearts the sudden supply of nutrient material contained in 
the blood does not cause any stoppage whatever, but a simple gradual improvement in 
the contractions. Upon the hypothesis suggested above this means that in consequence 
of the sudden supply of blood the whole energy available is in the one case engaged 
in the growth of the protoplasm from the raw material, so that no contractions can 
take place, while in the other it is distributed more equally over the different processes 
going on in the muscle. 
Op. cit. 
t Op . cit . 
